chore: Fix several style lints (#17488)

It's not comprehensive enough to start linting on `style` group, but
hey, it's a start.

Release Notes:

- N/A

crates/client/src/user.rs

@@ -200,7 +200,7 @@ impl UserStore {
                                 cx.update(|cx| {
                                     if let Some(info) = info {
                                         let disable_staff = std::env::var("ZED_DISABLE_STAFF")
-                                            .map_or(false, |v| v != "" && v != "0");
+                                            .map_or(false, |v| !v.is_empty() && v != "0");
                                         let staff = info.staff && !disable_staff;
                                         cx.update_flags(staff, info.flags);
                                         client.telemetry.set_authenticated_user_info(